Method of cleaning tube bundles



W. M. ZINGG Filed Nov. 18, 1959 METHOD OF CLEANING TUBE BUNDLES Oct. 23, 1962 INVENTOR Warren M Z 1'09 9 HGEN United States Patent 3,060,064 METHOD OF CLEANING TUBE BUNDLES Warren M. Zingg, Tulsa, ()kla, assignor to The Dow Chemical Company, Midland, Micln, a corporation of Delaware Filed Nov. 18, 1959, Ser. No. 853,933 4 Claims. (Cl. 1342) This invention relates to a method of cleaning tube bundles and particularly to a method of cleaning heat exchanger tube bundles having unwanted deposits on external surfaces of the tubes.

In the past, deposits collecting on the tubes of heat exchanger bundles have been removed by such means as soaking the bundle in a vat, and then sawing, scrubbing or prodding by hand. Bundles have also been cleaned by a wet sandblast technique which involves jetting the bundles with water containing sand at pressures up to 2,000 pounds per square inch. The above methods either are excessively time consuming, work on some soft deposits and not on other types of deposits, or cause erosion of the metal.

Accordingly, a principal object of this invention is to provide an improved method of cleaning tube bundles.

In accordance with this invention, unwanted deposits adhering to the tubes in a sheet bundle are removed by subjecting the tubes successively to a flame to at least partially char the unwanted deposits, then quenching (if need be) any burning matter by jetting steam thereon, and then jetting water onto said deposits on the tubes at pressures of the order of 1,000 to 3,000 pounds. A coolant fluid may be circulated through the tubes while subjecting the tubes to the action of the flame.

The invention, as well as additional objects and advantages thereof will best be understood when the following detailed description is read in connection with the accompanying drawing in which:

FIG. 1 is a side elevational view, in section, of apparatus for carrying out the method of this invention;

FIG. 2 is an end elevational view of the apparatus shown in FIG. 1, and

FIG. 3 is a diagrammatical view showing the apparatus for circulating coolant fluid through the tubes during the cleaning of external surfaces thereof.

Referring to the drawings, and particularly to FIGS. 1 and 2, there is shown tube bundle cleaning apparatus comprising a pair of tube bundle supporting and rotating members 10, 1011 which each comprise spaced apart beams having a pair of suitably journalled rolls 12 disposed in parallel spaced apart relationship. At least one of the rolls 1?. is driven by a suitably geared motor 14 through coupling means 16.

A hollow upright member 13, 20 is disposed at one end of each of the tube supporting and rotating members 10, a, respectively. Each upright member 18, 20 contains a longitudinally extending screw 22, 24 to which is coupled a laterally extending beam member 26 which extends between the upright members 18, 20 (and beyond the member 20). A wheel 28 at the upper end of each screw 22, 24 is used to rotate the screw and raise or lower the laterally extending beam member 26. A pulley 30, 32 is coupled to the laterally extending member 26 near each end thereof and an endless, flexible belt, chain or other suitable drive member 40 is carried by the pulleys. The pulley 32 is on a common shaft with a drive pulley 34 which is driven by an electric motor 36 mounted near the end 38 of the lateral member 26 and carried by the member 26.

Mounted along the flexible drive member 38 are three nozzles 42, 44, 46. The nozzle 42 is a gas flame jet nozzle, the nozzle 44 is a steam nozzle, and the nozzle 46 is a water or liquid jet nozzle.

7, 3,050,054 Patented Oct. 23, 1962 'ice,

Each nozzle 42, 44, 46 is coupled through the hoses or flexible pipes 48, 50, 52, respectively, .to its source of gas, steam or liquid (not shown).

A tube bundle 54, having test heads '56, 58 coupled to the open ends of the tubes is carried on the rolls 12 and may be rotated, on the rolls, around its longitudinal axis by means of the driven roll. Each test head 56, 58 has a suitable header 60, 62 whereby Water or other coolant fluid may be pumped through the tubes 63 of the bundle 54 during the cleaning operation. The header 56 has a vent plug 55 (shown at the top in FIGS. 1 and 2) which may be opened to vent air as the tube bundles are filled with coolant. The outlet header 62 rises somewhat above the top of the tube bundle in order to permit the bundle 54 to be filled with water or other coolant.

FIG. 3 illustrates in diagrammatical form, a means for circulating coolant fluid from an open reservoir to the test head 56 through a pipe 62 and pump 64. The return coolant passes from the test head 58 through an open ended tube or pipe 66 to the reservoir 60. As indicated, a heater unit '68 is indicated below the reservoir 60 to pre-heat, if desired, the coolant fluid before it is pumped through the tube bundle 54.

In operation, Water or pre-heated water may be circulated through the tubes to prevent excessive temperature differences between the tubes being flame treated and those not in the path of the flame jet from the nozzle 42 when the deposit is heavy or otherwise liable to generate large amounts of heat while being charred. Excessive temperature diiferences would tend to cause stresses in the tube bundle which would cause leaks at the rolled ends of the tubes 63 or would cause warpage of the tubes. Similarly, if no coolant were used and the heating is great, the heated tubes would probably expand more than the unheated ones and be forced out of their header plates (at the ends of the individual tubes). The use of a coolant in the tubes while the deposit is being heated aids in loosening the deposit from the tubes as the deposits are expanded by heating while the expansion of the tubes is minimized by cooling.

The three nozzles are placed in operation with all the nozzles 42, 44, 46 near the left end of the laterally extending member 26 and started moving to the right across the tube bundle 54 by means of the drive member 38. The flame from the nozzle 42 at least partially chars the deposits on those tubes 63 in the path of the flame, causing deposits thereon to have a somewhat brittle surface. If the deposit continues to burn after the flame jet passes along the' tube bundle, the burning is quenched by the jet of steam from the nozzle 44. However, if the deposit does not continue to burn, the quenching operation is omitted. The charred (or partially charred) deposit is then subjected to jets of water (or fluid such as brine or other non-flammable liquid) from the nozzle 46 at pressures of 2,000 pounds to 3,000 pounds or more per square inch, depending on the rating of the pumps available. In instances when the flame from the charring flame jets tends to spread to the remainder of the bundle, the burning is quenched by the jets of steam before the flame can spread, even though the charring may have been insuflicient. Further passes are made with the flame jet and steam jet in operation to complete the charring, then the deposit is subjected to the action of the jets of water. Other non-flammable gases such as nitrogen or carbon dioxide may be used in place of steam for quenching.

It is recognized that in some instances the use of water or other suitable liquid jetted at the tube bundle at pressures of around 2,500 to 3,000 pounds per square inch will remove foreign deposits without the flame charring step being used. However, especially when the deposits are rubbery, tough, or spongy they are best removed when I 3 at least partially charred before the high pressure water jets impinge on them.

During the cleaning of the tube bundle the jet nozzles 42, 44, 46 traverse along the length of the tubes from one end to the other. 'The nozzles are then returned to the starting end, the laterally extending beam 26 is raised or lowered slightlyby rotation .of the screws 22, 24 to present uncleaned tubes to the jets and the cleaning process continues. When the bundle is clean in that area facing the jets, the bundle is rotated to present an uncleaned area to the jets.

Alternatively, a nozzle arrangement having a central flame nozzle flanked on each side by a. steam or fog nozzle and a Water jet nozzle may the used. With appropriate switching to the jet nozzles the nozzle streams are used in correct sequence (that is, in the order of direction of movement; flame, steam and water). Such an arrangement permits continuous cleaning without removing the nozzles back to the indexing point before each cleaning traverse of the nozzles.

What is claimed is:

1. The method of cleaning unwanted charrable deposits from a tube bundle which comprises circulating a coolant through said tube bundle, directing a flame sequentially along the tube bundle to be cleaned and at 7 to expand as it circulates.

4. The method of claim 1, wherein said flame and jet of liquid are passed simultaneously in predetermined sequence along said tube bundle.

References Cited in the file of this patent UNITED STATES lATENTS 769,091 Kitsee Aug. 30, 1904 1,898,809 Berg Feb. 21, 1933 1,939,112 Eulberg Dec. 12, 1933 2,058,388 Rendleman Oct. 20, 1936 2,653,115 Drews Sept. 22, 1953 2,684,330 French July 20, 1954 2,685,293 Dauphinee Aug. 3, 1954 2,717,845 Carter Sept. 13, 1955 2,776,230 Scott Jan. 1, 1957 2,857,922 Efiinger Oct. 28, 1958 

1. THE METHOD OF CLEANING UNWANTED CHARRABLE DEPOSITS FROM A TUBE BUNDLE WHICH COMPRISES CIRCULATING A COOLANT THROUGH SAID TUBE BUNDLE, DIRECTING A FLAME SEQUENTIALLY ALONG THE TUBE BUNDLE TO BE CLEANED AND AT LEAST PARTIALLY CHARRING SAID DEPOSITS AS THE FLAME IMPINGES THEREON, AND THEN DIRECTING AT LEAST ONE JET STREAM OF LIQUID AT HIGH PRESSURE ONTO SAID AT LEAST PARTIALLY CHARRED DEPOSITS ON SAID BUNDLE ADJACENT TO THE POINT ON THE TUBE BUNDLE WHERE THE FLAME WAS DIRECTED. 